I'm unconvinced by Cruel and Tender, Martin Crimp's new take on on the "War on Terror". There's a certain over-artfulness in its art, a shallowness in its metaphor. Put it beside coruscating theatrical imaginations like Howard Barker (whose play The Castle remains one of the political masterpieces of recent British theatre) or the visceral sexual politics of Sarah Kane, and its lustre dims considerably.

The first play of Crimp's that I encountered was the genuinely impressive Attempts on her Life, and on reflection I think this vertigo-inducing text, with its cumulative excavation of the way mediated representations enter and distort our realities, is a much more pertinent and powerful comment on our times than Cruel and Tender, despite the latter's overtly contemporary attention to issues like the war in Iraq. This play is an updated take on Sophocles' tragedy The Trachiniae, or The Women of Trachis, and I can't help thinking it might have been more interesting to stage the original play.Sophocles' tragedy has the grand clarity of Classical Greek theatre, in which human action is drenched in a kind of transparent inevitability, the capricious workings of Destiny or the Gods on fragile mortals. It is based on the myth of the hero Herakles, who in the opening scene is away from home conquering Euboas, a region of Greece. He sends some of his booty - the captured princess Iole - to his pining wife Deianeira. Alarmed and jealous, Deianeira sends her erring husband a shirt impregnated with the blood of a centaur who tried to rape her and was killed by Herakles. In his dying moments, the centaur told her that his blood will magically ensure her husband's fidelity.

But the centaur, predictably perhaps, turns out to be vengeful rather than generous. The shirt has a very different effect to that Deianeira intends - Herakles is stricken with a "blood-fed flame" that devours his skin, and in his agony seeks the escape of death. When Deianeira's son Hyllus charges her with murdering his father, Deianeira kills herself. In the final scene, Herakles orders Hyllus to kill him, to release him from his agony, and to marry Iole, both of which charges he accepts reluctantly.

Crimp follows this basic storyline, but updates it with contemporary references. Herakles becomes a General (Jacek Koman) who is pursuing the hydra-headed War on Terror by means of bloody campaigns in Africa. Deianeira is his spoiled wife Amelia (Catherine McClements) , who is waiting his return amid rumours that her husband is a war criminal. Iole is Laela (Ratidzo Mambo), an African princess for whom the General has razed an entire town. The Chorus is replaced by Amelia's attendants, and various messengers and other dramatic dogsbodies become UN or government officials. The centaur's blood is transformed into a phial of biochemical liquid, the gift of a former spurned lover who now works in a germ warfare institute.

On the evidence of this play, Crimp simply doesn't possess a tragic muse. And while he deftly handles the various levels of language - from high Classical rhetoric to naturalism - it doesn't translate into effect. It's a play written with avowedly political intent but, unlike its model, it suffers from a certain metaphorical fuzziness. If it's meant to be read as an analogy - and this is what it seems to ask - it actually doesn't throw any but the most general of illuminations over our darkly flickering modern world.

The notion of terror as a hydra which grows two heads each time one is slashed off is one I can get, sure. But that's a very minor motif. A reference to germ warfare rebounding on those who use it is fine - but as a love philtre - even a revengeful love philtre - it's beginning to stretch even my credulity. The idea of the war hero-turned-criminal, spurned and betrayed by those who initially supported him, is perhaps more interesting - but the public politics of this durable theme is better pursued in Shakespeare's Coriolanus. Crimp's main point is to set the play in Amelia's bedroom, looking to sexual politics as a metaphor for warfare. In doing so, whether he intends to or not, he literally domesticates the politics of the War on Terror.

It's not as if this idea hasn't been explored before, and brilliantly: the connections between war and sexuality were assayed with damning force by Sarah Kane, most notably in her play Blasted. What Kane has, and Crimp lacks, is a heightened sexual anger, and the ability to express it. This difference is perhaps best discussed by looking at the character of Laela, the General's African mistress whom he has sent to Amelia to care for until his return.

Laela is all Otherness, knowingly exploiting her sexuality as material leverage. Her violent capture, despite her initial refusal to speak, seems to disturb her surprisingly little: she is a willing accomplice in her own subjugation. Her main concern is to be "nice" to the General so he will buy her the dresses she wants. Perhaps this is an ironic portrayal of the Stockholm Syndrome, or perhaps this is Crimp's commentary on corrupt regimes complicit with the War on Terror; but to my mind it backfires badly. If Laela is meant to symbolise "Africa", or any nation ravaged by the West's "diplomacy by other means", it's a portrayal full of the traditional Imperialist cliches: Africa is amoral, grasping, childlike, inscrutable, and willingly connives in its own rape.

In the original tragedy, the captured princess Iole is not from a distant land, but from a neighboring province of Greece. Her grief and shock at her abduction by Herakles is conveyed with poignancy and dignity by her total refusal to speak: her muteness holds all her protest. The transformation of this character into Laela matches the mutation of the character of Deianeira - queenly, distracted and tough - into the egocentric narcissism of Amelia.

The metaphoric blur that results is partly because of a collision between the literal realities to which the play is referring and the poetic myth of the original tragedy. There's nothing wrong with keeping both aspects in play, but I never felt free to enter either reality: somehow, instead of highlighting each other, they cancelled each other out.

Cruel and Tender was originally produced (in English) at the Théâtre des Bouffes du Nord, directed by Luc Bondy, who commissioned it. From what I have read, Bondy's production foregrounded the media portrayals of the "War on Terror" and the knickknacks of contemporary technology, and may have filled out some of the complexities and ambiguities signally lacking in the MTC version, directed here by Julian Meyrick.

And perhaps my doubts arise as much from Meyrick's rather one-dimensional and sometimes clunky production as from any shortcomings in the script itself. Amelia's cry that she is not a victim resonates especially uneasily. In this play, she is nothing but a victim, a bored and faithless trophy wife eating her heart out for her absent husband, and she suffers her fate in gratifyingly traditional ways.

In this production, which lacks any ironic distancing, the gesture towards the archetype of the "strong woman" remains only a gesture. “I could be mistaken for a victim,” cries a defiant Amelia, “and, that’s not a part I’m prepared to play!” This is not a feminist rallying cry, as it is played: like everyone else, Amelia is a victim. Her defiance is a luxury, the result of her privilege, which comes at a terrible and unacknowledged cost to others. This subtext is simply absent from Meyrick's production.

The performances themselves are never less than competent, but I feel that most of the cast has problems in pitching the differing registers of the text as it shifts from realism to mythic grandeur. Many of the more heightened passages or monologues are actually obscured by the music which rises, increasingly predictably, to signal another "poetic" bit. The stage comes alive late in the play when the General (Jacek Koman) finally appears, horribly disfigured by his disease. Koman, always a reliably skilled and committed actor, is the only one who really handles Crimp's challenging shifts in linguistic register.

The design - basically a naturalistic bedroom of hotel-style blandness and luxury - is unsuited to the Fairfax Studio, where the audience sits diagonally on two sides of the stage. Like Luc Bondy's original production, the design of which was more abstract and clinical, it features a reflective window back stage. Behind the darkened glass, lighted figures can suddenly appear and vanish. It's an interesting device; but on a stage that is not a proscenium arch its effects are obscured from those who aren't watching it front on - which includes at least a third of the Fairfax audience.

In short, Cruel and Tender strikes me as a fair bit of sound and fury signifying, when you really examine it, surprisingly little. On the other hand, this is the latest in a number of recent productions which confront the important issues of our times and, if nothing else, it places theatre squarely in the charged social arena where it belongs.